Storage vessel



Aug. 21, 1962 R. IRVINE 3,050,208

STORAGE VESSEL Filed Sept. 25, 1959 2 Sheets-Sheet 1 Fig. l 'v 30INVENTOR ROBERT L. IRVINE BY MM Him- ATTORNEY Aug. 21, 1962 R. IRVINE3,050,208

STORAGE VESSEL Filed Sept. 25, 1959 2 Sheets-Sheet 2 mu E '2 i i 1 l WMilli] INVENTOR. ROBERT L. IRVINE CLILMH. W

ATTORNEY ite States The present invention relates to a storage vessel,and more particularly to a storage vessel for storing large quantifiesof volatile liquids that have a normal boiling point below prevailingatmospheric temperatures, such as ammonia, butane, butadiene, chlorine,ethylene, liquefied petroleum gases (L.P.G.), propylene, and sulphurdioxide.

L.P,G. comprises principally either propane or butane, or mixturesthereof, and is widely used both industrially and by the general publicfor a vast number of uses. The storage of L.P.G., particularlycommercial propane, has long presented a problem, since when the same isused for urban heating, the amount consumed per unit of time is apt tobe enormous.

Where natural facilities for underground storage are lacking, resortmust be had to above-surface storage facilities. Also, undergroundstorage offers problems with regard to the contamination of the liquidbeing stored. The construction of suitable above-surface storage vesselsconstitutes an economic problem. Refrigerated storage offers merit forstorage of large quantities of the liquids by reducing the internalpressure which must be contained through reducing the vapor pressure ofthe fluid being stored. If the internal pressure to be contained in thevessel is reduced to slightly above atmospheric, a cylindrical form ofthe vessel ofiers economic merit as this form is easily constructed.However, the cost of manufacture for above-surface roofs (which must begas-tight in respect to the remainder of the tank), is apt to beconsiderable.

This invention has an object the provision of a novel storage vessel.

This invention has as another object the provision of a novel storagevessel of relatively low cost for the abovesurface storage of volatilefluids such as L.P.G.

This invention has as yet another object the provision of a novelstorage vessel having a roof of low cost construction.

Other objects will appear hereinafter.

For the purpose of illustrating the invention there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

Referring to the drawings wherein like chaacter references refer to likeparts:

FIGURE 1 is a fragmentary view of the upper portion of the storagevessel of the present invention before the fabric portion of the roofthereof has been expanded.

FIGURE 2 is a view similar to that of FIGURE 1 but showing the fabricportion of the roof of the storage vessel in expanded disposition.

FIGURE 3 is fragmentary vertical sectional view revealing the finishedstorage vessel construction of the pressent invention.

Referring to the drawings, the storage vessel of the present inventionshown in FIGURE 3 is designated generally as 10.

The storage vessel comprises a steel cylindrical tank atent 12 to whicha flat tank bottom 14 may be welded. The specific construction of thetank bottom forms no part of the present invention, although a suitableform of tank bottom may be poduced by butt welding steel plates. Theflat tank bottom 14 and the cylindrical tank 12 are supported on aconcrete ring 16.

The mode of construction for the cylindrical tank 12 likewise forms nopart of the present invention. However, such cylindrical tank 12 ispreferably formed by butt welding successive courses of steel plates.When the successive courses are vertically welded and horizontally giithwelded, it is advisable to fill the cylindrical tank 12 with treatedwater. This will help preserve the desired roundness of the cylindricaltank 12 and provide stability against wind forces.

When the desired height for the cylindrical tank 12 has been attained,construction of the roof of the storage vessel is begun.

The roof of the storage vessel designated generally as 18 comprisesthree layers which are sandwiched together (see FIGURE 3 The innermostlayer 20 comprises a woven flexible fabric of either metal fiibers,fiberglass fibers, or synthetic fibers, such as nylon, which has beenthoroughly impregnated with a flexible coating of low permability, suchas neoprene. The roof 18 is formed in the shape of a hemisphere, withthe bottom annular margin of the innermost layer 20 being securedlyjoined to either the inner or outer wall surface of the cylindrical tank12 through an adhesive joint 22.

While a wide variety of strong fabrics impregnated with clastomericmaterials may be utilized to form the innermost layer 20 of the roof 18,where, as in the illustrated embodiment, such innermost layer 20comprises a neoprene impregnated nylon, it is desirable that theinnermost layer 20 be cemented to the cylindrical tank 12 by an epoxyresin adhesive. Such epoxy resin adhesives present the required highstrength adhesive characteristics,

and durability, required for fixedly securing the innermost layer 20 toeither the inner or outer Wall surface of the cylindrical tank 12. Whileepoxy resin adhesives are to be preferred, it is of course, to beunderstood that other adhesives may be utilized.

The degree of overlap of the annular margin of the innermost layer 20 tothe upper wall surface of the cylindrical tank 12 should be sufiicientto provide the required anchorage strength characateristics for the roof18. By providing the annular margin for the adhesive joint 22 with avertical height equal to one foot, sufiicient overlap is provided foranchoring an innermost layer 20 formed of neoprene impregnated nylon tosteel using an epoxy resin adhesive for most sizes of construction.

After the fabric layer 20 is inflated to the position shown in FIGURE 2in the manner as will be descibed, an insulating layer 24 of a rigidfoam polymer is adhered to the outer surface of the fabric layer 20. Apreferred rigid foam polymer insulation layer 24 is one formed frompolyurethane, although other foamed plastics may be utilized. Thethickness of the rigid foam polymer insulation layer 24 required isgoverned by the thermal insulation desired since a three inch thicknessis more than adequate to be self-supporting and to withstand the windand other forces prevailing on the roof 18.

The innermost fabric layer 20 of the roof 18 provides bulk of desiredtensile properties and the adhering insulation layer 24 provides thedesirable compressive properties. The insulation layer 24 also serves toprotect the inner fabric layer 20 from weather exposure and ultravioletrays which may adversely affect the fabric layer 20.

A vapor barrier layer 26 is povided over the rigid foam polymer layer24. The vapor barrier layer 26 may comprise an application of one ormore coatings of a low permeability material, such as aluminum pigmentedvinyl chloride acetate resin. A long lasting impervious coating whichalso adds to the composite strength of the roof 18 is a fiberglassreinforced epoxy layer applied to the outer surface of the rigid foampolymer 24.

V The cylindrical shell .12 is insulated by courses of thin flat metalsheathing 36, such as aluminum sheathing, which are coiled around andspaced from the outer surface of the cylindrical shell 12. Thebottommost course of the sheathing 36 is seated on the flat tank bottom14, and is adhered to the flat tank bottom 14 by an epoxy adhesive joint38. The remaining courses of sheathing 36 are in overlapped relation andare joined together by an epoxy adhesive. The space between the coursesof sheathing 36 and the cylindrical shell 12 is filled with a rigid foampolymer 34. It is desirable that the vapor barrier layer 26 of the roof18 be continuous with or overlap the sheathing 36.

The storage vessel preferably includes at least one suitably sealedporthole 28, which may serve as a manhole for gaining access to theinterior of the vessel. A vapor outlet fitting 30 is provided at the topof the roof 18 and may be of a size so as to also serve as a manhole.

A plurality of valved ducts 32a and 3211 provided at the top and bottomof the storage vessel 10 permit contolled introduction and removal ofthe liquid stored in the vessel 10. It is preferred that the incomingliquid be introduced through the top duct 32a and the liquid bewithdrawn from the vessel 10 through the bottom duct 32b.

The storage vessel 10 also includes a refrigerating unit 40 formaintaining the fluid at a temperature whereby the vapor pressure of thefluid is within the design range of the interior pressure of the vessel.10. By using a refrigerating unit 40 of the regenerative refrigerationtype, the liquid within the vessel 10 can be maintained at its propertemperature, and at the same time the liquid be stored within the vessel10 can be used as a refrigerant.

The roof 18 of the present invention may be formed 'both rapidly andcheaply. Thus, the first stage of the formation of the roof 18 is shownin FIGURE 1. In this stage, the prefabricated innermost layer 20 isadhesively secured to the cylindrical tank 12. This is accomplished byadhesively joining the inner face of the annular margin of the innermostlayer 20 to the outer face of the cylindrical tank 12 as has heretoforebeen indicated by an adhesive joint 22. The innermost layer 20 isreadily prefabricated, and is light in weight (approximately 20-22ounces per yard for 1500 ASTM grab material) so as to enable the entireinnermost layer 20 to be suspended by the same erection equipment usedfor the cylindrical shell 12. The prefabricated layer 20 is also easilytransported from the prefabricator in a rolled up condition. By joiningthe fabric layer 20 to the outer face of the cylindrical tank 12, theadhesive joint 22 can be accomplished readily from the outside of thecylindrical tank 12, and is there'- fore preferred.

The next stage of the formation of the roof 18 for the storage vessel 10of the present invention is shown in FIG- URE 2. In this stage theinnermost layer 20 is expanded upwardly to its full height so that itpresents a hemisphere. .This is preferably accomplished by firstsubstantially filling the cylindrical tank 12 with treated water, andthen intro ducing an inert pressurized gas, such as nitrogen, as throughthe valved duct 32a located in the upper portion of the cylindrical tank12. Such pressurized gas serves to inflate the innermost layer 20,namely it distends the innermost layer 20 to the disposition shown inFIGURE 2 from the collapsed disposition shown in FIGURE 1.

When the innermost layer 20 has been distended as seen in FIGURE 2, therigid foam polymer layer 24 is applied to the innermost layer 20. Suchrigid foam polymer layer 24 not only serves as an insulation for thestorage vessel 10, but since it is a continuous layer of a pennanentlyset shape, and since it adheres to the innermost layer 20, it serves asa structural skeleton for fixing the innermost layer 20 in its distendeddisposition.

When the rigid foam polymer layer 24 has been applied, the vapor barrierlayer 26 is then applied to the tank, as by means of a spray gun or thelike, in order to prevent water vapors entering the rigid foam polymerlayer 24 from low temperature service.

The insulation is applied around the cylindrical tank 12 by firstplacing the bottommost course of sheating 36 around the tank .12 andthen filling the space between the bottommost course of the sheathing 36and the tank 12 with the foam polymer insulation 34. The next course ofthe sheathing 36 is placed around the tank 12 overlapping the outer andupper surface of the bottommost course of the sheathing 36, and againthe space between the sheathing 36 and the tank 12 is filled with thefoam polymer 34. The procedure is followed until the entire height ofthe tank 12 is covered by the sheathing 36 and the foam polymer 34.

The apparatus and method of the present invention .enables a storagevessel having a hemispherical dome or roof to be constructed at arelatively low cost. The combina tion of the innermost layer and therigid foam polymer layer insures gas-tightness, while the adhesion of anannular margin of appreciable height further insures gastightnessbetween the'roof 18 and the cylindrical tank 12.

The present invention may be embodied in other speci fic forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification as indicating the scope of theinvention I claim:

1. A storage vessel for volatile liquids comprising a metal cylindricaltank having a hemispherical roof, with said hemispherical roofcomprising an innermost layer of a fabric impregnated with an elastomer,said elastomer impregnated fabric being adhesively secured to the wallsurface of said cylindrical tank about an annular margin at the top endof said cylindrical tank, and an outer insulation layer of a foampolymer secured to the outer surface of said innermost layer.

2. A storage vessel in accordance with claim 1 in which the foam polymeris coated with a vapor barrier layer of a low permeable material.

3. A storage vessel in accordance with claim 2 wherein said vaporbarrier layer is an aluminum pigmented vinyl fluoride acetate resin.

4. A storage vessel in accordance with claim 2 in which the fabricimpregnated with an elastomer is nylon impregnated with a syntheticrubber and the foam polymer is polyurethane foam.

5. A storage vessel in accordance with claim 4 in which the elastomericimpregnated fabric is adhesively secured to the outer surface of thecylindrical tank.

6. A storage vessel for volatile liquids comprising a metal cylindricaltank having a hemispherical roof, said hernisperical roof comprising aninnermost layer of fabric impregnated with an elastomer, said elastomerimpregnated fabric being adhesively secured to the wall surface of saidcylindrical tank about an annular margin at the top end of saidcylindrical tank, and with said cylindrical tank and the innermost layerof said hemispherical roof each being covered with a continuousinsulation layer of a foam polymer secured to the outer surface of themetal cylindrical tank and to the outer surface of the innermost layerof said hemispherical roof.

7. A storage vessel in accordance with claim 6 including a vapor barriercoated on said foam polymer and thin metal sheathing surrounding thefoam polymer around said tank.

8. A storage vessel in accordance with claim 6 including a thin met-a1overlapped sheathing surrounding the insulation layer of foam polymeraround the cylindrical 5 tank.

References Cited in the file of this patent UNITED STATES PATENTS1,918,335 Heylandt July 18, 1933 10 6 Morrison May 15, 1951 Hagopian eta1. Oct. 9, 1956 Meyer .Dec. 9, 1958 Morrison June 9, 1959 Lewis Dec. 1,1959 FOREIGN PATENTS Great Britain June 11, 1958 France June 22, 1955

